I think DEX is Procs, not Crits. So if you had an augment in your weapon, something like
https://everquest.allakhazam.com/db/item.html?item=123647 you stack DEX to make it proc more as you swig (as I remember it.. I'm a necro, I don't melee).
Necro Crit rate is increased by our Epic (4%, 8%, 10%) and the AA line Critical Affliction starting in Gates of Discord (and the size of the Crit is increased by the AA line Destructive Cascade starting in Secrets of Faydwer).
Edit much later to add: There is also an AA line to make direct Life Taps crit, and all INT casters have lines to make Direct Damage spells (aka Nukes) crit.. but mostly I care about the DoTs DoTs, baby.
Edited, Mar 16th 2018 8:26am by Felicite